Pulverizing mill with replaceable screen means



3 Sheets-Sheet 1 INVENTOR. Gustav H. Frongquist ATTORNEY April 12, 1955 G. H. FRANGQUIST PULVERIZING MILL WITH REPLACEABLE SCREEN'MEANS Filed March 12,,1954

April 12, 1955 G. H. FRANGQUIST- 2,706,087

PULVERIZING MILL WITH REPLACEABLE SCREEN MEANS Filed March 12, 1954 :s Sheets-Sheet 2 Fig. 2.

44 INVENTOR.

Gustav H. Fro ngquist I JTTORNEY 5 Sheets-Sheet 3 v INVENTOR. Gustav H. Frungquist G. H. FRANGQUIST PULVERIZING MILL WITH REPLACEABLE SCREEN-MEANS Aprillz, 1955 Filed Marh 12, 1954 ATTORNEY United States Patent PULVERIZING MILL WITH REPLACEABLE SCREEN MEANS Gustav H. Frangquist, Chicago, 11L, assignor to Combustion Engineering, Inc., New York, N. Y., a corporation of Delaware Application March 12, 1954, Serial No. 415,750

Claims. (Cl. 241-86) This invention relates to pulverizing mills of the screen type and in particular to a novel mounting for the screen of a screen mill to provide easy removal.

Screen mills of the type have heretofore had the screen integrally built into the lower portion of the mills housing enclosing the grinding chamber and this made it very difiicult to inspect and replace the screens.

lt is an object of this invention to provide a novel screen carrying unit which is independent of the mill housing and may be easily removed from the mill.

Additional objects and advantages will become apparent from the following description of illustrative embodiments of the invention when read in conjunction with the accompanying drawings wherein:

Fig. l is a longitudinal side elevation of a screen mill embodying the invention.

Fig. 2 is a transverse cross section through the mill taken on line 22 of Figs. 1 and 3.

Fig. 3 is a side elevation taken on line 33 of Fig. 2

of tne novel screen carrying unit.

Fig. 4 18 an end elevation of Fig. 3 taken on line 4-4 of Figs. 3 and l.

Fig. 5 is a plan view of Fig. 3 as taken on line 5-5 of Fig. l.

Fig. 6 is a fragmentary section taken on line 66 of Figs. 4 and 5.

Fig. 7 is a fragmentary section taken on line 77 of Figs. 4 and 5.

in Figs. 1 and 2, the mill comprises a base 1 upon which are mounted bearings 2 supporting a shaft 3. The base 1 has portions 4 (Fig. 2) extending upwardly and inwardly of the bearings 2 which form half bearings 5 supporting a screen carrying unit generally designated as S. A cover 6 together with the screen carrying unit S form a housing for the grinding chamber 7. The shaft 3 extends transversely through chamber 7 and discs 8 are fastened at right angles to the shaft. Rods 9 are circumferentially spaced around the shaft 3 and are supported by the discs 8. The grinding hammers 10 are hinged on the rods 9, the length of their outer axially extending portions occupying substantially the full width of the grinding chamber 7.

The cover 6 has hubs 11 extending outwardly and shaped to fit closely adjacent the shaft 3. The bottom edges 12 (Fig. l) of the cover 6 he substantially in a plane passing through the center line of shaft 3 and the covers flanged ends 13 and 14 (Fig. 1) fit onto end portions 15 and 16 extending upwardly from the base 1. The cover may be hinged at 17 around which it swings counterclockwise away from the mill chamber It may be clamped in closed position by yokes 18 hinged at 19, the yokes being provided, with set screws 20 which bear against lugs 6a on the cover 6.

The screen carrying unit S (Figs 1, 2, 3) comprises two transversely spaced apart semi-circular symmetrically similar plates 21 extendingnormal to shaft 3, each plate being provided adjacent its center with a semicircular trunnion 22 shaped on its inner side 23 to fit closely adjacent the shaft 3 and on its outer side 24 to fit in the half bearing 5 (Fig. 2) on the portion 4 of the base 1. The upper edges 26 of the trunnlons 22 (Fig. 3) and the upper edges 27 of the plates 21 he substantially in a plane passing through the center line of the shaft 3 and fit against the bottom edges of the covers hubs 11 and the covers bottom edges 12 (Fig. 1) to form a tight joint. In Figs. 3 and 5, the plates 21 are held apart by spacer members 28 and 29 fastened thereto as by bolts 30 and 31. Member 28 is provided with a shoulder 32 (Fig. 7) which engages a shoulder on a yoke 33. A screen 34 extends around the major portion of the peripheral shoulders 35 of the plates 21 (Figs. 2, 3) and has bars 36 and 37 fastened to and extending along its transverse edges (see also Figs. 6, 7). A second shoulder 38 on yoke 33 (Fig. 7) engages the lower edge of bar 36 on screen 34 and the yoke may be clamped to spacer member 28 by a lock nut 39 on bolt 40 which is fastened to the member and passes through a hole in yoke 33 provided therefor. Spacer member 29 is provided with a lip 41 (Fig. 6) extending outside of bar 37. Just below spacer member 29 are cylindrical cams 42 (one in each plate 21; Figs. 1, 5, 6) which may be rotated around their axis and are each provided with a flat face 43 (Fig. 6). When rotated into the position shown in dotted lines in Fig. 1 and in full in Fig. 6, the face 43 engages the bottom edge of bar 37 on screen 34 and holds it in place snugly up against the peripheral shoulders 35 of the plates 21. A square end 44 on cams 42 (Fig. 3) permits rotation by a wrench and a lock nut 45 clamps it in position.

The gap between the spacer member 29 and the flange 13 of cover 6 (Figs. 1, 6) is sealed by a member or members 46 (Fig. 1) which include upwardly extending members of the base 1 into which fit tube or tubes 47 through which the material to be ground is fed into the grinding chamber 7. Each tube 47 contains a motor driven screw feeder 48 which receives the unground material from a hopper 49 and delivers it into the grinding chamber 7.

In operation the material within the grinding chamber 7 is broken up by the impact of the numerous rapidly rotating hammers 10 until it is sufiiciently reduced in size to pass out through the screen 34 in the lower half of the mill. To obtain different sizes of fineness of grinding, a number of screens having different openings are provided. Should the screen 34 require inspection or replacement, the cover 6 is removed which in this disclosure requires rotating it counterclockwise around the hinge 17. The screen carrying unit S when so released, may now be rotated clockwise about its trunnions 22 in half bearing 5 to bring the screen 34 above the base 1. One end of the screen 34 is released by loosening the lock nuts 45 '(Fig. 5) and turning the cams 42 (Fig. 6) counterclockwise so that the holding bar 37 on this end of the screen is free to move across the flat faces 43 of the cams. The yoke 33 is removed by removing the lock nuts 39 (Fig. 7). The holding bar 36 of screen 34 is now released and this end of the screen is free to be removed. The holding bar 37 at the end of the screen adjacent the cams 42 may now he slid out from under the cams and the screen 34 removed from the mill.

While the preferred embodiment of the invention has been here shown and described, it will be understood that changes in construction, combination and arrangement of parts may be made without departing from the spirit and scope of the invention as claimed.

I claim:

1. In a screen mill, a housing enclosing a grinding chamber having a removable cover and a screen carrying unit below said cover, a base, a shaft extending transversely across said chamber and supporting grinding hammers, bearings supporting said shaft on said base and bearings mounted on said base supporting trunnions on said screen carrying unit, said screen carrying unit comprising spaced apart plates extending transversely to said shaft and a screen formed to extend around a major portion of lower edges of said plates and fastened thereto, said trunnions being provided on said plates adjacent said shaft, the meeting edges of said housing cover and of said screen carrying unit forming a sealed joint, said screen carrying unit, upon removal of said cover, being rotatable on said trunnions to a substantially opposite position to provide access to the screen.

2. In a screen mill, a housing enclosing a grinding chamber having a removable cover and a screen carrying unit below said cover, a base, a shaft extending transversely across said chamber and supporting grinding hammers, bearings supporting said shaft on said base and bearings concentric with said shaft mounted on said base supporting trunnions on said screen carrying unit, said screen carrying unit comprising spaced apart semicircular symmetrically similar plates extending transversely to said shaft and a screen formed to extend around a major portion of the arcs of said plates and fastened thereto, said trunnions being provided adjacent each of said plates center and said shaft, the meeting edges of said housing cover and of said screen carrying unit contacting to form a continuous joint, said screen carrying unit, upon removal of said cover, being rotatable around said shaft on said trunnions to a substantially diametrically opposite position to provide access to the screen.

3. In a screen mill, a housing enclosing a grinding chamber having a removable cover and a screen carrying unit below said cover, a base, a shaft extending transversely across said chamber and supporting grinding hammers, bearings supporting said shaft on said base and half bearings concentric with said shaft mounted on said base supporting trunnions on said screen carrying unit, said screen carrying unit comprising spaced apart semicircular symmetrically similar plates extending transversely to said shaft and concentric therewith and a screen formed to extend around a major portion of the arcs of said plates and fastened thereto and spacer members fastened to and extending between said plates adjacent the transverse edges of said screen, said trunnions being positioned adjacent each of said plates center and said shaft, each trunnion being shaped semicylindrically and on its inner side to fit closely adjacent said shaft and on its outer concentric side to fit one of said half hearings on said base, said housing cover having semi-cylindrical hubs each shaped to fit closely adjacent said shaft and to align with and contact the adjacent trunnion to form a joint and said covers edges and the adjacent edges of said plates contacting to form a continuous joint, said screen carrying unit, upon removal of said cover, being rotatable around said shaft on said trunnions to a substantially diametrically opposite position to provide access to the screen.

4. In a screen mill, a housing enclosing a grinding chamber having a removable cover, and a screen carrying unit below said cover, a base, a shaft extending transversely across said chamber and supporting grinding hammers, bearings supporting said shaft on said base and half bearings concentric with said shaft mounted on said base supporting trunnions on said screen carrying unit, said screen carrying unit comprising spaced apart semicircular symmetrically similar plates extending transversely to said shaft and a screen formed to extend around a major portion of the arcs of said plates and spacer members fastened to and extending between said plates adjacent the transverse edges of said screen, said trunnions being provided adjacent each of said plates center and said shaft, clamp bars fastened to and extending along said screens transverse straight edges, a removable yoke engaging one of said bars on said one screen edge and the adjacent spacer member and rotatable cams which upon rotation in one direction engage the other of said bars on said other screen edge, the meeting edges of said housing cover and of said screen carrying unit contacting to form a continuous joint, said screen carrying unit, upon removal of said cover, being rotatable around said shaft on said trunnions to a diametrically opposite position to provide access to the screen.

5. A screen carrying unit for a screen mill comprising spaced apart semi-circular plates extending transversely to said mills hammer supporting shaft, a screen extending around the major portion of the arcs of said plates and terminating in edges substantially parallel to said shaft and spacer members fastened to and extending between said plates adjacent said edges of said screen, clamp bars fastened to and extending along said screens edges, a removable yoke engaging one of said bars at one screen edge and the adjacent spacer member to hold said screen in position and rotatable cams mounted in said plates which upon rotation in one direction engage the other of said bars on said other screen edge and exerting a tension on said screen to force it tightly against the arcs of said plates.

No references cited. 

